1. Field of the Invention
The present invention relates to concrete mixers and in particular to concrete strengthening and adhesion material feeder apparatus for producing a mix for fibrous concrete i.e. concrete strengthened and improved adhesion by the addition of concrete strengthening and adhesion material.
2. Description of the Prior Art
Certain problems arise during the production of such a fibrous concrete mix as the fibres have to be evenly distributed throughout the mix in order for the maximum benefits to the concrete to be achieved. In particular the feed of the fibers into the mix has to be such that the fibers are not formed into "balls" rather than being evenly distributed throughout the mix.
It is therefore the general object of this invention to provide a concrete strengthening and adhesion material feeding machine which overcomes the above problems and which produces a mix, to add in any desired proportions, of cement, aggregate and fibers.
A concrete strengthening and adhesion material feeding machine in accordance with the invention comprises a feed for concrete strengthening and adhesion material and aggregate incorporating a hopper for material, a means to separate and process said material, a metering means and a discharge outlet.
The use of a concrete strengthening and adhesion material hopper of this nature ensures that the material are fed evenly to the processing means and the danger of fibres of metal or other types of material being attracted together by self-magnetism or self-sticking and being formed into balls is substantially reduced.
Conveniently the hopper is reciprocated over an material combing and separating means.
The equipment is suitable for any form of concrete strengthening and adhesion material and the flow of material can be changed so that the size and shape of the material is appropriate to the particular type of material and to the feed desired. Equally, the feed of concrete strengthening and adhesion material may be varied by varying the depth or frequency of reciprocation of the compressor in the hopper, by varying the level of concrete strengthening and adhesion material maintained in the hopper during operation, or by varying the size of the outlet from the hopper.
Preferably concrete strengthening and adhesion material is fed to the hopper through a delivery opening and the opening and the compressing means may be vibrated to assist even flow of material. If the delivery opening is disposed over the mouth of the hopper then the level of concrete strengthening and adhesion material contained therein can be maintained substantially constant as the hopper reciprocates beneath the feed end of the processing means.
The concrete strengthening and adhesion material feeding apparatus may be mounted on wheels or on slides for reciprocal movement across its outlet port.
The concrete strengthening and adhesion material may be made of metal, plastics, glass or any other convenient material and may be made of any desired shape or configuration to suit the desired ultimate concrete mix.
The flow of concrete strengthening material may be varied by varying the speed of rotation of the impeller-agitator combination by adjusting the size of the adjustable metering gate.
The apparatus may also include a blowing unit into which works in conjunction to the feeding apparatus comprises a venting hopper connected to a source of pressurized air. The mix on entering the hopper is manipulated so that an even flow of material may be discharged from the hopper by the air pressure through an outlet port. This device helps to ensure an even supply of mix to the concrete through the outlet port and thus prevents surging.
Recent years have seen an upsurge in the use of fiber reinforced concrete. Structures formed of fiber reinforced concrete have superior strength over unreinforced concrete and, in many instances, can be employed in lieu of concrete reinforced with reinforcing rods or bars (rebars) to provide similar strength at lesser cost.
Various fibers have been employed. Most often, steel fibers are used, but in many instances, ceramic fibers, such as glass fibers, have been employed. Typically, the fibers are dispersed randomly within the mix and the structures resulting from a pour of the mix. As a consequence, the maximum reinforcement provided by a given number of fibers cannot be achieved. Those fibers parallel to the direction of a bending force application to the concrete structure provide no reinforcing whatsoever, while those fibers only slightly angled with respect to the direction of the bending force application provide but minimal reinforcement. Consequently, it has been necessary to incorporate in such concrete, a far greater number of fibers than actually necessary to ensure that proper reinforcing will be achieved with such a random distribution.
This, in turn, has posed not only an economical problem due to the cost of the increased amount of fibers, but a labor problem as well. When used in the large amounts required, the fibers have a tendency to adhere to each other or "ball." When balls are left in the poured concrete, a weak spot is formed. Moreover, the presence of such balls impedes finishing operations. Accordingly, it has been necessary to manually retrieve the fiber balls from the concrete as it is being poured and finished.
Fine aggregates comprising river or mountain sand or artificial particles are widely used to prepare cement mortar or line stone type hydraulic mortar which is used to construct buildings or many other civil structures.
Although the composition and particle size of the sand also influences the quality of the product, so long as sand collected from the same source is used it is easy to utilize the sand having the same composition and particle size and it is rare to admit sands from different sources. When the sand contains particles of different size it is easy to classify them into fine, medium and coarse particles with a sieve and a small difference in the particle size does not result in a great difference in the quality of the product.
Numerous innovations for concrete strengthening and adhesion material feeding apparatus have been provided in the prior art that are adapted to be used. Even though these innovations may be suitable for the specific individual purposes to which they address, they would not be suitable for the purposes of the present invention as heretofore described.